Is it stalling during that process at 38% ?
If so there are at least two workarounds. Disable multicore and virtualization features during the install (you can re-enable them afterwoods) or install in another machine and transfer the HD back.

The Smart Array Controller (B120i) will probably not work for any version of pfsense (or FreeBSD for that matter).

That controller requires a closed source driver and in linux it requires you to download a driver (kernel module I think) for each version of the linux kernel (like a different driver for RH6.0, 6.1, 6.2 & 6.4).

My work around was to disable the RAID controller in BIOS and enable legacy SATA support. Yeah, I know I lose hardware raid but I can live with that because all the systems I'm deploying are failover pairs.

BTW - will pfsense officially support software RAID at some point in the future? I'm hesitant to use any feature that the developers aren't confident about….

Turn off the software raid in bios, and it should work fine. Otherwise Throw ESXi on it, which HP has included raid drivers for (Use the HP ISO!), and then put it in a vm.. It will work fine. For a buddy of mine we chose the latter, so besides initial install/basic configuration nothing else was really tested under bare hardware/pfSense install.

I am running pfSense on this EXACT platform, but inside of ESXi…You might want to consider putting it in a VM to avoid driver issues. ESXi is a commercial product which means the drivers are often kept up to date. The good thing about esxi is that if you have few enough cores you can run it for free.